6,258 research outputs found
Automatic Dataset Labelling and Feature Selection for Intrusion Detection Systems
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Correctly labelled datasets are commonly required. Three particular scenarios are highlighted, which showcase this need. When using supervised Intrusion Detection Systems (IDSs), these systems need labelled datasets to be trained. Also, the real nature of the analysed datasets must be known when evaluating the efficiency of the IDSs when detecting intrusions. Another scenario is the use of feature selection that works only if the processed datasets are labelled. In normal conditions, collecting labelled datasets from real networks is impossible. Currently, datasets are mainly labelled by implementing off-line forensic analysis, which is impractical because it does not allow real-time implementation. We have developed a novel approach to automatically generate labelled network traffic datasets using an unsupervised anomaly based IDS. The resulting labelled datasets are subsets of the original unlabelled datasets. The labelled dataset is then processed using a Genetic Algorithm (GA) based approach, which performs the task of feature selection. The GA has been implemented to automatically provide the set of metrics that generate the most appropriate intrusion detection results
Homogenization of a Dirichlet semilinear elliptic problem with a strong singularity at in a domain with many small holes
We perform the homogenization of the semilinear elliptic problem
\begin{equation*} \begin{cases} u^\varepsilon \geq 0 & \mbox{in} \;
\Omega^\varepsilon,\\ \displaystyle - div \,A(x) D u^\varepsilon =
F(x,u^\varepsilon) & \mbox{in} \; \Omega^\varepsilon,\\ u^\varepsilon = 0 &
\mbox{on} \; \partial \Omega^\varepsilon.\\ \end{cases} \end{equation*} In this
problem is a Carath\'eodory function such that a.e. for every , with in some
and a function such that and for every . On the other hand the open sets
are obtained by removing many small holes from a fixed
open set in such a way that a "strange term" appears in the
limit equation in the case where the function depends only on .
We already treated this problem in the case of a "mild singularity", namely
in the case where the function satisfies . In this case the solution to the problem
belongs to and its definition is a "natural" and
rather usual one.
In the general case where exhibits a "strong singularity" at , which is the purpose of the present paper, the solution to
the problem only belongs to but in
general does not belongs to any more, even if
vanishes on in some sense.
Therefore we introduced a new notion of solution (in the spirit of the
solutions defined by transposition) for problems with a strong singularity.
This definition allowed us to obtain existence, stability and uniqueness
results
A semilinear elliptic equation with a mild singularity at : existence and homogenization
In this paper we consider semilinear elliptic equations with singularities,
whose prototype is the following \begin{equation*} \begin{cases} \displaystyle
- div \,A(x) D u = f(x)g(u)+l(x)& \mbox{in} \; \Omega,\\ u = 0 & \mbox{on} \;
\partial \Omega,\\ \end{cases} \end{equation*} where is an open
bounded set of ,
is a coercive matrix, is continuous, and
, with
and , if , if ,
if , a.e. .
We prove the existence of at least one nonnegative solution and a stability
result; moreover uniqueness is also proved if is nonincreasing or
"almost nonincreasing".
Finally, we study the homogenization of these equations posed in a sequence
of domains obtained by removing many small holes from a fixed
domain
Electromagnetic topology: Characterization of internal electromagnetic coupling
The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference
A virtual robot solution to support programming
Computer programming is a valuable skill. But learning programming is sometimes difficult, time-consuming, even frustrating. In this context, there is a need for new approaches to help in the process of learning programming. Here it is presented a solution based on a virtual robot with progressive system and supported in a generic and portable language. Those features answer to some needs. First, the virtual robot allows for certain level tangibility to the results. Then, the implementation as a progressive system allows for the support of the learning process. Finally, the use of a generic and portable language allows for the installation of the system on many platforms.info:eu-repo/semantics/acceptedVersio
Adding Contextual Information to Intrusion Detection Systems Using Fuzzy Cognitive Maps
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.In the last few years there has been considerable increase in the efficiency of Intrusion Detection Systems (IDSs). However, networks are still the victim of attacks. As the complexity of these attacks keeps increasing, new and more robust detection mechanisms need to be developed. The next generation of IDSs should be designed incorporating reasoning engines supported by contextual information about the network, cognitive information and situational awareness to improve their detection results. In this paper, we propose the use of a Fuzzy Cognitive Map (FCM) in conjunction with an IDS to incorporate contextual information into the detection process. We have evaluated the use of FCMs to adjust the Basic Probability Assignment (BPA) values defined prior to the data fusion process, which is crucial for the IDS that we have developed. The experimental results that we present verify that FCMs can improve the efficiency of our IDS by reducing the number of false alarms, while not affecting the number of correct detections
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